A liquid crystal panel in a liquid crystal display comprises a substrate, and a surface of the substrate is filled with a plurality of liquid crystal molecules. By controlling the arrangement direction of the plurality of liquid crystal molecules, the effect of displaying a different image may be achieved. In the liquid crystal panel, in order to achieve control of liquid crystal molecules, it is necessary to align a plurality of liquid crystal molecules such that the plurality of liquid crystal molecules located on the substrate surface are arranged uniformly in the same direction.
In the prior art, the substrate surface is made to have an alignment capability by causing a friction roller to roll relative to the substrate surface. In particular, the friction roller is a cylinder with an outer surface being wrapped with friction cloth, and the surface of the friction cloth is provided with a plurality of fibers. When the friction roller is rolling on the substrate surface along a set direction, the fibers on the friction cloth can exert to the substrate surface a pressure perpendicular to the substrate surface and a friction force along the direction in which the friction roller is rolling, such that alignment grooves with a consistent direction are formed on the substrate surface. Then, a plurality of liquid crystal molecules are dripped into the alignment grooves of the substrate surface, such that the liquid crystal molecules are uniformly arranged on the substrate surface according to a certain direction along the alignment grooves, realizing alignment of the plurality of liquid crystal molecules.
If there is a step on the surface of the substrate (i.e., a difference in height between the substrate surface and a preset plane), then when the friction roller is rolling on the substrate surface along a set direction, the pressure exerted by the fibers of the friction cloth on the friction roller to a portion of the substrate surface with a step is different from that to a portion without a step, such that the deformation of the fibers of the friction cloth is different when the friction roller is rolling. When the friction roller continues rolling on the substrate surface along the set direction, since the deformation of the fibers of the friction cloth on the friction roller is different, the depths of the alignment grooves formed on the substrate surface by the fibers of the friction cloth will be inconsistent, such that the plurality of liquid crystal molecules can not be located in one and the same plane, and thereby the reflection of light rays will be different. This will produce stripes on the liquid crystal panel and thus affect the display effect.